Gas generator and cartridge therefor

ABSTRACT

The gas generator includes a heat responsive means which communicates the reaction chamber with the liquified gas in the reservoir in order to pressurize and to flush out the liquified gas from the reservoir as well as a pressure responsive means which communicates the reaction chamber with the aspirating chamber in order to mix the reactive gases of the reaction chamber with the vaporized gas. The cartridge is insertable as a unit into the gas generator housing so as to be readily assembled and replaced.

United States Patent 1 Crane Jan. 9, 1973 [54] GAS GENERATOR ANDCARTRIDGE THEREFOR [75] Inventor: Michael Crane, West Orange, NJ.

[73] Assignee: General Pneumatics Corporation,

Orange,N.J.

221 Filed: Feb.12, 1971 21 App1.No.: 114,989

[52] US. Cl. ..62/50, 62/52, 60/3848 [51] Int. Cl. ..F17c 7/02 [58]Field of Search .....60/38.48, 251; 62/45, 50, 52,

[56] References Cited UNITED STATES PATENTS 3,431,743 3/1969 Green..62/52 3,481,149 12/1969 Crane ..62/45 Primary Examiner-Meyer PerlinAssistant Examiner'-Rona1d C. Capossela Attorney-Kenyon Kenyon ReillyCarr & Chapin [57] ABSTRACT The gas generator includes a heat responsivemeans which communicates the reaction chamber with'the liquified gas inthe reservoir in order to pressurize and to flush out the liquified gasfrom the reservoir as well as a pressure responsive means whichcommunicates the reaction chamber with the aspirating chamber in orderto mix the reactive gases of the reaction chamber with the vaporizedgas. The cartridge is in sertable as a unit into the gas generatorhousing so as to be readily assembled and replaced.

21 Claims, 1 Drawing Figure PATENTEUJAN 9 ma BY W GAS GENERATOR ANDCARTRIDGE THEREFOR This invention relates to a gas generator and acartridge therefor. More particularly, this-invention relates to a gasgenerator for producing and delivering a gas from a stored liquified gasand aself-contained reaction chamber cartridge for gas generators.

Heretofore, various gas generators have been known in which a liquifiedgas such as carbon dioxide or Freon have been maintained in a liquifiedstate in a reservoir for subsequent vaporization into a gas. In order topro vide sufficient heat for vaporization of the liquified gas, variouscombustible charges have been located within the gas generator inproximity to the reservoir of liquified gas so as to generate a quantityof heat upon ignition which can be used to heat up the liquified gas toa vaporized state. For example, as described in U.S. Pat. No. 3,481,149,a gas generator has been known in which a device containing a reactivecharge of material and defining an axial passage extendingconcentrically of the charge has been mounted within a reservoir ofliquified gas so that upon ignition of the charge, sufficient heat isproduced to cause a heat exchange between the liquified'gas flowingthrough the central passage and the reacted charge.

The various gas generators which have been previously used, particularlythose which are portable, have found wide utility, for example, in theinflation of flotation equipment, such as life rafts or jackets, andsafety convenience equipment such as inflatable slides, pads or-mattresses. However, despite such wide useage, these previous gasgenerators have had certain inherent deficiencies. For example, one ofthe deficiencies has been that the working fluid has been overheatedbefore being expelled from the gas generator. Another deflciency hasbeen that the working fluid has been inadequately mixed with the hotgases which have been generated by the reactive mixtures used in the gasgeneratorsfAlso, in the case of Freon, the Freon has frequent decomposedso as to form corrosive substances. These various deficiencieshaveresulted in the burning,'weakening, porosity and other damage to theinflatable devices with which they have been used.

Accordingly, it is an object of this invention to provide a gasgenerator which prevents the overheating of aworking fluid.

lt is another object of the invention to mi-xtheworking'fluid ofa gasgenerator with the generated hot gases ofa combustible charge within thegas generator.

It is another object of the invention to provide a gas generator whichprevents the decomposition ofa Freon working fluid within a gasgenerator.

It is another object of the invention to reduce the possibility ofdamage to an inflatable device from a gas generator. 1 g

It' is another object of the invention to prevent the damage of aninflatable device from the inflating gases ofa gas generator.

Briefly, the gas generator of the invention has a housing which definesa reservoir for containing a liquified gas, means within the housingdefining a reaction chamber for a heat generating means, a passage meanswhich extends through the reaction chamber to conduct a liquified gasfrom the reservoir in heat exchange relation with the heat generatingmeans in the reaction chamber for vaporization of the liquified gas, anda heat responsive means-between the reaction chamber and the reser voirfor venting the reaction chamber to the reservoir in response to thegeneration of a predeterminedtemperature in the reaction chamber. Inaddition, the gas generator includes a pressure responsive means forcommunicating the reaction chamber with the aspirating section of thereservoir in response to the existence of a predetermined pressuredifferential between the reaction chamber and the aspirating section ofthe reservoir.

The housing which defines the reservoir is of any suitable material suchas metal in order to contain a liquified gas under pressure and includesan aspirating or mixing chamber at an outlet end wherein the vaporizedgas and hot gases of combustion can mix together prior to passing out ofa discharge port in the housing. In addition, the housing isprovided'with a suitable fitting so as to be charged with a liquifiedgas, such as carbon dioxide, Freon or other suitable liquified gas.

The means defining the reaction chamber is constructed in the form of acartridge which can be placed within the housing as a self-containedunit and which can be replaced at suitable intervals. The cartridge in-vcludes a casement means, for example, of cylindrical shape which definesat least one reaction chamber, for example, of annular orcompartmentalized structure, in which a suitable heat generating meansis contained. The heat generating means may be in any suitable form,such as, a solid chemical cartridge of pellet form,

' a liquid phase combustible product, a fuel grain powder or any othersuitable material. The cartridge further has an axially extendingcentral passage which is separated from the reaction chamber, forexample, by a heat exchange tube secured to the casing so as to definethe heat exchange passage.

The heat responsive means is secured in a wall of the casement means ofthe cartridge for venting the reaction chamber to the exterior of theeasement means in response to the generation of a predeterminedtemperature in the reaction chamber due to the combustion of the heatgenerating means. For example, the heat responsive means is in the formof a nozzle which has a fusible plug disposed across the opening'of thenozzle. The fusible plug is made of a material which melts upon beingsubjected to a predetermined temperature from the hot gases producedwithin the reac tion chamber so that the opening of the nozzle isexposed to the'passage of the hot gases. The temperature responsivemeans can also be formed of fusible plugs which are softened by the heatgenerated within the reaction chamber and which are ejected due to apredetermined pressure differential between the reaction chamber and thereservoir.

The pressure responsive means is also secured in the casement means ofthe cartridge and includes a passage between the reaction chamber andthe aspirating chambers at the exterior of the'cartridge and a pressureresponsive disc which is disposed across the passage in sealed relation.The disc is constructed soas to be ruptured upon the existence of apredetermined pressure differential between the reaction chamber and theaspirating chamber. In this way, the hot reactive gas can be mixed withthe vaporized gas so as to be diluted prior to passage out of thegenerator.

The cartridge is further provided with a trap between the reactionchamber and the pressure responsive means so as to trap solidparticulate particles from passing from thereaction chamber to thepressure which defines the reservoir proper for the liquified gas andincludes an outwardly extending neck and another of which fits into theneck and-defines the aspirating chamber. The cartridge, in turn,- isprovided with a shoulder at one end which projects from the contour ofthe cartridge so as to seat against a corresponding shoulder or ledgewithin the neck of the housing while the base of the cartridge seats ona floor of the housing. The part of-the housing whichdefines theaspirating chamber is secured over the shoulder'of the cartridge withinthe neck'of the housing so as to secure the cartridge in place.f r v Inorder tolignite the heatgenerating means within the cartridge, asuitable ignition means is mounted in the housing of the gas generatorto communicate with the reaction chamber. In one embodiment, theignition means is in the form of a flame jet ignitor which-includes aretaining pin which secures a firing pin in set position, a spring-whichis compressed .when the firing pin is in' the set position and whichexpels the firing pin against a percussion cap of an explosive cartridgewhen the retaining pin is released. The explosive cartridge is used toproduce a flame jet which can be directed'into the reaction chamber forigniting the heat generating means. In order to preserve the sealedintegrity of'the cartridge when used with such an ignition means, asuitable fitting is mounted in the cartridge with a disc sealed acrossapassageway therethrough. When the flame jet of the, ignitor assembly iscreated, the heat of the jet is used to rupture the disc so as to permitpassage of the flame jet into the reaction chamber. In

another-embodiment, a friction ignitor can be utilized for the ignitionmeans. I

The heat generating means. within the reaction chamber can be formed 'ofany suitable reactable materials which are, activated, for example, byfriction heating, sparking, or percussion. For example, the heatgenerating means can be in the form of chemically reactive materialswhich produce an exothermic reaction. Such a reaction can be achieved byigniting a fuel grain powder containing sulfur,- carbon, potassium bleor a mechani'cally-rupturable material. In one embodiment,'the closuredisc can be ruptured at the same have passed through the pressureresponsive means between the reaction chamber and the aspiratingchamber.- ln still another embodiment, the closure discs can be rupturedby a suitable mechanical device such as a cable membranev tearingmechanism which embodies a scored closuredisc, a hardened tear ring, a

pull ring connected to the tear ring and a cable secured to the pullring. The closure disc can also be weakened by hot gases alone or inconjunction with an exothermic reaction of chemicals situated on thesurface of the disc to permit the liquified gas contained in thereservoir to escape through the discharge port.

Where an explosive shock is used to fracture the rupture disc within afitting leading to the reaction chamber, the shock can also beusedtoimpinge upon the closure disc across the discharge port to rupture theclosuredisc;

In use, once the heat generating means has been ignited by'the'particular ignition means used with the gas generatonheat is givenoff from the reaction chamber through the heat exchange tube to theliquified gas in the heat exchange passage. The liquified gas thusbecomes heated to a vaporized'state and passes out of the discharge portof'the generatoronce theclosure disc has been fractured. As this processcontinues, the fusible plugs of the heat responsive means melts andallow venting of the'hot gases inthe reaction chamber to the reservoirupstream of the heat exchange passage; This pressurizes the liquifiedgas. in the reservoir. to expel and flush the liquified gas from thereservoir. As a result, the gas which leaves the gas generator is a coolgas. v

Asthe operation of the gas generator continues, the pressure generatedwithin the reaction chamber'by the hot gases therein causes theoccurrence ofa pressure differential across the discs of thepressureresponsive means sufficient to rupture the discs. Upon rupture ofthese-discs, the reaction chamber gases are vented to the aspiratingchamber where they are mixed with the vaporized gasso that the hot gasesare diluted to anextent sufficient to prevent a concentration of'the hotgases in the device being suppliedwith the gas of the generator. I

These and-other objectsand advantages of the invention will become moreapparent from the following detailed description and appended claimstaken in con-. junction with the accompanying drawing in which:

The drawing illustrates a cross-sectional view of a gas generatorconstructed 'in accordance with the invention.

Referring to the drawing, the gas generator 10 includes a housing 11formed of two parts 12, 13. The lower part l2,'as viewed, is of bulbousconstruction with an upstanding "neck 14 and defines a reservoir thereinfor containing a liquified gas 15 such as carbon dioxide or Freontherein while the upper part 13 is.of

generally cylindrical shapewith a conical upper portionv so as to definean aspirating and mixing chamber 16 g and a discharge port 17. In orderto secure the two .parts 12, 13 together, each is provided with matingthreads 18, 19 along suitable surfaces. In addition, a

' seal ring 20 is sealingly seated between the two parts 12, 13 so as toprevent leakage past the threaded surfaces. Also, in order to seal thedischarge port 17, a closure disc 21 is disposed across the mouth of theport 17 and is held in place, for example, by a hose connector 22suitable for attachment to a gas utilization device (not shown). Thehose connector 22 is secured, as by threading, to the exterior surfaceof the upper housing part 13. The closure disc 21 is made of anysuitable material which can be ruptured or fractured, for example, byheat, pressure, chemical or mechanical means. For example, the closuredisc 21 can be provided with a heat responsive coating on the insidesurface so as to rupture in response to a predetermined temperature inthe aspirating chamber 16. Also, the closure disc 21 can be pressuresensitive so as to fracture when the pressure within the chamber 16reaches a predetermined level or the disc may be fractured physically bya suitable tool. In order to withstanding the pressure and temperatureto which the housing 11 will be subjected and also to provide a safetyfactor which will prevent any undesired release of liquified gas, thehousing parts 12, 13 are formed of a suitable metallic material. Also,either of the housing parts 12, 13 is provided with a suitable valve, asis known, to charge the liquified gas into the housing 11.

A cartridge 23 which provides a self-contained reaction assembly isremovably disposed within the interior of the housing 11 and is ofgenerally cylindrical contour to slide through the neck 14 of the lowerpart 12 of the housing 11. This cartridge 23 is formed of a cylindricalcasement means 24 such as a shell of hollow construction, a pair ofshouldered discharge plugs 25, 26 which are threadably secured in theopposite ends of the shell 24 and a heat exchange tube 27 which extendsconcentrically within the cylindrical shell 24. The shell 24'and heatexchange tube 27 are mounted in spaced relation to each other so as todefine a reaction chamber 28 of annular shape. The reaction chamber 28can also be compartmentalized by suitable partition walls (not shown) soas to define a plurality of individualcompartments.

The cartridge 23 also contains a plurality of heat generating means 29,such as cartridge or pellets ofchemically reactive exothermic materialssuch as a fuel grain powder 29', within the reaction chamber 28. Inaddition, the shell 24 has an integral annular wall 30 thereon whichextends radially inwardly into sealed relation with the heat exchangetube 27 so as to segregate the reactive materials 29' in the reactionchamber 28 from the upper discharge plug 25. This wall 30 includes atortuous passage 31 therethrough which serves as a baffle to trap solidparticulate particles from passing from the reactor chamber 28 to theupper plug 25. In this instance, the baffle utilizes the greatermomentum of the solid particlesto prevent them from following the pathof the gases generated by the reactive materials 29 and to cause them todeposit on the baffle surfaces,

The wall 30 also includes one or more sockets 32 into which a reactivematerial cartridge 29 is fitted as well as a passage 33 whichcommunicates the socket 32 with the opposite side of the wall 30.

The shell 24 also has one or more heat responsive means 34corresponding, for example, to thenumber of reactive material cartridges29 disposed in the outer wall. Each heat responsive means 34 is formedof a fusible plug nozzle, as is known, which includes a nozzle having apassage therethrough to communicate the reaction chamber 28 with thereservoir of liquified gas 15 and a fusible plug which is disposed insealing relation across the nozzle passage. Thefusible plug is of a heatresponsive material which melts at a predetermined temperature forexample, in the range of 200 to l,200 P so as to open the nozzlepassageway and vent the reaction chamber 28 to the reservoir of gas 15.

The discharge plugs 25, 26 which are secured in the shell 24 alsoreceive the ends of the heat exchange tube 27 within recessed portions35 in a snug fit relation while sealing rings 36 are positioned withinsuitable grooves 37 to seal the tube 27 to the plugs 25, 26 againstleakage.

In addition, the upper discharge plug 25 is provided with at least onepressure responsive means 38 for each reactive material cartridge 29 inorder to communicate the reaction chamber 28 with the aspirating chamber16 in response to a predetermined pressure differential therebetween.Each pressure responsive means 38 is constructed of a centrallyapertured fitting 39 which is threadably secured into a counterboredaperture 40 in the plug 25 and a rupture disc 41 which is located withinthe aperture 40 between a shoulder of the aperture 40 and the fitting38. The rupture disc 41 thus serves to seal the passage between theaperture 40 of istence of apredetermined pressure differential acrossthe disc 41, for example, a pressure in the range of 25 psig to 1,800psig.

The upper discharge plug 25 is also providedwith a fitting 43 similar tothe other fittings 39 which includes a rupture disc 44 disposed within acounterbore 45 of theplug 25 and which is threaded into the bore 45 tosecure the disc 44 in place. However, this fitting 43 is elongated toextend upwardly from the plug 25 to communicate with an ignitionassembly 46. The bore 45 is further positioned directly in alignmentwith the passage 33 in the baffle wall 30 'of the shell 24. I

The upper discharge plug 25 is also formed with an annular shoulder 47which projects from the remainder of the plug 25 and rests upon a ledge48 on the internal surface of the lower housing part 12; In addition,the

upper housing part 13 is abutted against the shoulder 47 of the plug 25so as to clamp the plug 25 between the two parts 12, 13 of the housing11. A suitable sealing ring 49 is also disposed in a groove 50 betweenthe ledge 48 and the annular shoulder 47 of the plug 25.

The lower discharge plug 26 is formed .with. a depending collar-likeextension 51 which is suitably apertured to permit passage of theliquified gas therethrough into the heat exchange tube 27. In addition,the floor 52 of the lower housing part 12 is provided with a pluralityof thrust stops 52', for example, three, so as to center the plugextension 51 and, in turn, the cartridge 23 therein. Also, a fillervalve 53 of known construction is secured within the discharge plug 26to communicate with the reaction chamber 2'8 so as to introduce apressurized gas therein.

The ignition assembly 46 is provided with a hollow stem 54 which isthreadably mounted through a threaded bore 55 within the upper housingpart 13 and which is slidably disposed within the fitting 43 with a sealring 56 therebetween. The stem 54 includes a passage 57 therein whichcommunicates with the bore in the, fitting 43. In addition, the ignitionassembly 46 includes a retaining pin 58 which is removably mountedwithin a firing pin guide 63 and a hole in a fir-, ing pin'59 which isheld in its retracted position by the retaining pin 58 and a spring 60which biases the firing pin 59 in a direction towards a percussion cap61 of a shell type explosive cartridge 62 located within the stem 54.

in order to assemble the gas generator lO, the solid chemical cartridges29 are first placed in the reaction chamber 28 with the bottom plug 26removed. After loading, the bottom plug 26 is threadably engaged. in thecylindrical shell 24 and the reaction chamber 28 is pressurized with agas such as a mixture of oxygen, inert gas and hydrocarbon gas, throughthe filler valve 53.'The cartridge 23 is then inserted into the lowerhousing part 12 through the neck 14 so that the shoulder 47 of thecartridge plug rests on the ledge 48 adjacent the neck 14 of the housing11 while the bottom plug extension slides within the thrust stops 52'onto the floor 52 of the housing 11. The upper housing part is thenthreadably engaged in the internally threaded neck of the lower housingpart. 12 through the neck 14 so that the shoulder 47 of the cartridgeplug 25 rests on the ledge 48. adjacent the neck 14 of the housing 11while the bottom plug extension 51 slides within the thrust stops 52onto the floor 52 of the housing 11. The upper housing part to which theignition assembly has been previously attached is then threadablyengaged in the internally threaded neck of the lower housing part 12 soas to clamp the cartridge 23 in position. Thereafter, the closure disc22 is secured in place, so as to seal off the interior of the gasgenerator 10. Alternatively, the upper housing part 13 can be providedwith the-closure disc 21 prior to threaded engagement with the'lowerhousing part 12. Finally the reservoir is suitably charged with aliquified gas.

In use, in order to initiate the vaporization of the reservoirofliquified gas, the retainer pin58 of the ignition assembly 46 ismanually removed so that the firing pin 59 is released to impingeagainst the percussion cap 61;The explosive cartridge 62 then produces ashock wave which ruptures the disc 44 located within the fitting 43sothat the hot gases which'are generated by the explosive cartridge 62 andpass through the stem 54, bore 45 and passage 33 cause the burning ofagase- Alternatively, the exothermic reaction can be initiated by meansof a friction ignitor which consists of flint, abraisve and fusematerials which are activated by physical means. Alternate means ofopening the closure disc are suitable for some applications and consistof a cable membrane tearing mechanism which e mbodies a scored'closuredisc, a hardened tear ring and an attached -pull ring connected to acable.

Once the'cher'nical reaction takes place, the heat 'means 34 causing theplugs to be melted and ejected therefrom. This allows the hot gases fromthe reaction chamber 28') enter the reservoir 15 and force the liquifiedgas to discharge through, the heat exchange ous mixture and theignitionof the solid chemical cartridges 29 in thereaction chamber 28.In addition, the shock generated by the explosive cartridge 62 can alsobe used to fracture the rupture discs 41 in the pressure responsivemeans 38 so as to permit'the hot gases to impinge upon the closure disc21. The weakening of the closure disc 21 by the hot gases alone orinconjunction with the exothermic reaction of a chemical coating 1 on thesurface of the disc 21 allows the liquified gas contained in thereservoir to escape to the discharge port 17.

tube 27.

Since gaseous reaction products are also generated within the reactionchamber 28, a positive pressure also develops during use. Thus, when thepressure differential across .the rupture disc4l in each pressureresponsive means 38 becomes great enough, the disc 41 is fractured andthe gaseous reaction products enter the aspirating chamber 16 and; mixwith the exiting working fluid. As the gaseous reaction products of thereaction chamber 28 pass through the baffle passage 31, the solidparticles aretrapped. The baffle also serves as a heat shield to preventexcessive heat from reaching the disc material prior to being fracturedby pressurization. That is, overheating is avoided by preventing directimpingement of radiant heat from luminous reacting material on the discmaterial and by decreasing the rate of convective heat transfer to thedisc material by restricting the passage through which the hot gasesmust be transported.

The invention further provides a gas generator .in which the liquid gascanbe. ejected and flushed under a positive pressure from the reservoirso as to provide a more efficient use of the gas generator.

In addition, the invention. provides a gas generator which efficientlymixes the hot gases produced in the exothermic reaction of a heatgenerating means with the working fluid within the gas generator. Thisprevents the inflateddevice from being detrimentally influenced by aconcentration of the hot gases from the reaction chamber.

What is claimed is:

1. In a gas generator having a reservoir for a liquified gas, a reactionchamber within said reservoir for housing a heat generating means insealed relation to said reservoir, and a passage means extending throughsaid reaction chamber and communicating at each of the ends thereof withsaid reservoir to conduct a liquified means in response to apredetermined temperature condition in said reaction chamber subsequentto activation of the heat generating means in said reaction chamber todeliver a heated gaseous mixture from said reaction chamber to saidreservoir.

2. In a gas generator as set forth in claim 1 wherein said heatresponsive means includes at least one nozzle having a fusible plugtherein wherein said plug is melted in response to said predeterminedtemperature condition to cause said nozzle to communicate said reactionchamber with said reservoir.

3. In a gas generator as set forth in claim 1 which further includes apressure responsive means for communicating said reaction chamber withsaid reservoir downstream of said passage means in response to apredetermined pressure differential between said reservoir and saidreaction chamber.

4. ln a gas generator as set forth in claim 3 wherein said pressureresponsive means includes a passageway between said reservoir and saidreaction chamber and a rupture disc sealingly disposed within saidpassageway, said disc being rupturable in response to said pressuredifferential.

5. A gas generator comprising a housing defining a reservoir therein fora liquified gas;

first means within said housing including a hollow cylindrical shell anda heat exchange tube defining a reaction chamber for a heat generatingmeans, said reaction chamberbeing sealed from said reservoir;

a passage means extending through said reaction chamber andcommunicating at the ends thereof with said reservoir for. conducting aliquified gas therethrough in heat exchange relation with a heatgenerating means in said reaction chamber for vaporization of theliquified gas; and

heat responsive means mounted in said shell between said reactionchamber and said reservoir for venting said reaction chamber to saidreservoir in response to the generation of a predetermined temperaturein said reaction chamber.

6. A gas generator as set forth in claim 5 which further comprises Ipressure responsive means between said reaction chamber and saidreservoir for communicating said reaction chamber with said reservoir inresponse to the existence of a predetermined pressure differentialbetween said reaction chamber and said reservoir.

7. A gas generator as set forth in claim 6 wherein said heat responsivemeans communicates said reaction chamber with said reservoir upstream ofsaid passage means and said pressure responsive means communicates saidreaction chamber with said reservoir downstream of said passage means.

8. A gas generator as set forth in claim 6 which further comprises atrap located between said pressure responsive means and said reactionchamber for trapping solid particulate particles from passing from saidreaction chamber to said pressure responsive means.

9. A gas generator as set forth in claim 5 which further comprisesignition means for activating the heat generating means within saidreaction chamber to produce heat.

10. A gas generator as set forth' in claim 5 which further comprises theheat generating means in the form of a fuel grain powder within saidreaction chamber. A

11. A gas generator as set forth in claim 5 wherein said housing furtherdefines an aspirating chamber at one end in communication with saidreservoir for conducting vaporized gas therethrough out of said housing.

12. A gas generator as set forth in claim 5 which further comprises adischarge port at one end of said housing, a connector secured to saidhousing at said discharge port and a closure disc mounted between saidhousing and connector in sealed relationacross said discharge port.

13. A gas generator comprising a housing defining a reservoir thereinfor a liquified gas and a chamber atone end for aspirating a vaporizedgas therefrom;

a hollow cylindrical shell and a heat exchange tube defining a reactionchamber for a heat generating means within said housing in sealedrelation thereto;

a passage means extending concentrically through said heat exchange tubeand communicating at one end with said reservoir and at an opposite endwith said chamber for conducting a liquified gas therethrough in heatexchange relation with a heat generating means in said reaction chamberfor vaporization of the liquified gas; and

a pressure responsive means mounted'in said shell and said heat exchangetube between said reaction chamber and said aspirating chamber forcommunicating said reaction chamberwith said aspirating chamber inresponse to the existence of a predetermined pressure differentialbetween said chambers.

14. A cartridge for a gas generator comprising a casement means definingat least one reaction chamber and a heat generating means receivedtherein;

a heat responsive means secured in said casement means for venting saidreaction chamber to the exterior of said casement means in response tothe generation of a predetermined temperature in said reaction chamber;and i a pressure responsive means secured in said casement means forcommunicating said reaction chamber with the exterior of said casementmeans in response to theexistence of a predetermined pressuredifferential thereacross.

15. A cartridge as set forth in claim 14 which further comprises abaffle between said pressure responsive means and said reaction chamberfor trapping solid particulate particles from passing from said reactionchamber to said pressure responsive means.

16. A cartridge as set forth in claim 14 which further comprises a valvefitting in said casement for injecting pressurized gas into saidreaction chamber.

17. A cartridge as set forth in claim 14 wherein said heat responsivemeans includes at least one nozzle having a fusible plug thereincommunicating with said reaction chamber.

18. A cartridge as set forth in claim 14 wherein said pressureresponsive means includes a passageway between said reaction chamber andsaid exterior of said cross-section and surrounds said axial passage.

20. A cartridge as set forth in claim 14 which further comprises a plug.removably secured to said casement at one end thereof for closing saidreaction chamber to the exterior of said casement.

21. Acartridg'e as set forth in claim 20 which further comprises a valvefitting in said plug for injectingpressurized gas into saidreactionchamber.

1. In a gas generator having a reservoir for a liquified gas, a reactionchamber within said reservoir for housing a heat generating means insealed relation to said reservoir, and a passage means extending throughsaid reaction chamber and communicating at each of the ends thereof withsaid reservoir to conduct a liquified gas therethrough in heat exchangerelation with a heat generating means in said reaction chamber forvaporization of the liquified gas upon activation of the heat generatingmeans in said reaction chamber; heat responsive means for venting saidreaction chamBer to said reservoir upstream of said passage means inresponse to a predetermined temperature condition in said reactionchamber subsequent to activation of the heat generating means in saidreaction chamber to deliver a heated gaseous mixture from said reactionchamber to said reservoir.
 2. In a gas generator as set forth in claim 1wherein said heat responsive means includes at least one nozzle having afusible plug therein wherein said plug is melted in response to saidpredetermined temperature condition to cause said nozzle to communicatesaid reaction chamber with said reservoir.
 3. In a gas generator as setforth in claim 1 which further includes a pressure responsive means forcommunicating said reaction chamber with said reservoir downstream ofsaid passage means in response to a predetermined pressure differentialbetween said reservoir and said reaction chamber.
 4. In a gas generatoras set forth in claim 3 wherein said pressure responsive means includesa passageway between said reservoir and said reaction chamber and arupture disc sealingly disposed within said passageway, said disc beingrupturable in response to said pressure differential.
 5. A gas generatorcomprising a housing defining a reservoir therein for a liquified gas;first means within said housing including a hollow cylindrical shell anda heat exchange tube defining a reaction chamber for a heat generatingmeans, said reaction chamber being sealed from said reservoir; a passagemeans extending through said reaction chamber and communicating at theends thereof with said reservoir for conducting a liquified gastherethrough in heat exchange relation with a heat generating means insaid reaction chamber for vaporization of the liquified gas; and heatresponsive means mounted in said shell between said reaction chamber andsaid reservoir for venting said reaction chamber to said reservoir inresponse to the generation of a predetermined temperature in saidreaction chamber.
 6. A gas generator as set forth in claim 5 whichfurther comprises pressure responsive means between said reactionchamber and said reservoir for communicating said reaction chamber withsaid reservoir in response to the existence of a predetermined pressuredifferential between said reaction chamber and said reservoir.
 7. A gasgenerator as set forth in claim 6 wherein said heat responsive meanscommunicates said reaction chamber with said reservoir upstream of saidpassage means and said pressure responsive means communicates saidreaction chamber with said reservoir downstream of said passage means.8. A gas generator as set forth in claim 6 which further comprises atrap located between said pressure responsive means and said reactionchamber for trapping solid particulate particles from passing from saidreaction chamber to said pressure responsive means.
 9. A gas generatoras set forth in claim 5 which further comprises ignition means foractivating the heat generating means within said reaction chamber toproduce heat.
 10. A gas generator as set forth in claim 5 which furthercomprises the heat generating means in the form of a fuel grain powderwithin said reaction chamber.
 11. A gas generator as set forth in claim5 wherein said housing further defines an aspirating chamber at one endin communication with said reservoir for conducting vaporized gastherethrough out of said housing.
 12. A gas generator as set forth inclaim 5 which further comprises a discharge port at one end of saidhousing, a connector secured to said housing at said discharge port anda closure disc mounted between said housing and connector in sealedrelation across said discharge port.
 13. A gas generator comprising ahousing defining a reservoir therein for a liquified gas and a chamberat one end for aspirating a vaporized gas therefrom; a hollowcylindrical shell and a heat exchange tube defining a reaction chamberfor a heat generating means within said housing in sEaled relationthereto; a passage means extending concentrically through said heatexchange tube and communicating at one end with said reservoir and at anopposite end with said chamber for conducting a liquified gastherethrough in heat exchange relation with a heat generating means insaid reaction chamber for vaporization of the liquified gas; and apressure responsive means mounted in said shell and said heat exchangetube between said reaction chamber and said aspirating chamber forcommunicating said reaction chamber with said aspirating chamber inresponse to the existence of a predetermined pressure differentialbetween said chambers.
 14. A cartridge for a gas generator comprising acasement means defining at least one reaction chamber and a heatgenerating means received therein; a heat responsive means secured insaid casement means for venting said reaction chamber to the exterior ofsaid casement means in response to the generation of a predeterminedtemperature in said reaction chamber; and a pressure responsive meanssecured in said casement means for communicating said reaction chamberwith the exterior of said casement means in response to the existence ofa predetermined pressure differential thereacross.
 15. A cartridge asset forth in claim 14 which further comprises a baffle between saidpressure responsive means and said reaction chamber for trapping solidparticulate particles from passing from said reaction chamber to saidpressure responsive means.
 16. A cartridge as set forth in claim 14which further comprises a valve fitting in said casement for injectingpressurized gas into said reaction chamber.
 17. A cartridge as set forthin claim 14 wherein said heat responsive means includes at least onenozzle having a fusible plug therein communicating with said reactionchamber.
 18. A cartridge as set forth in claim 14 wherein said pressureresponsive means includes a passageway between said reaction chamber andsaid exterior of said casement and a rupture disc sealingly disposedacross said passageway, said disc being rupturable in response to saidpredetermined pressure differential.
 19. A cartridge as set forth inclaim 14 wherein said casement is cylindrical in shape and defines acentral axial passage and said reaction chamber is of annularcross-section and surrounds said axial passage.
 20. A cartridge as setforth in claim 14 which further comprises a plug removably secured tosaid casement at one end thereof for closing said reaction chamber tothe exterior of said casement.
 21. A cartridge as set forth in claim 20which further comprises a valve fitting in said plug for injectingpressurized gas into said reaction chamber.